Nobiletin, a flavonoid, appears to be the active ingredient in tangerines that provides the healthy benefits, researchers from the University of Western Ontario have discovered.
In a series of experiments on mice, the researchers discovered that nobiletin counter-acted the bad effects of the high fat, high sugar Western diet. The mice's cholesterol, insulin and glucose levels remained the same and they didn't develop a fatty liver. As a result, they didn't put on weight.
Nobiletin seems to be ten times more effective than naringenin, which is found in grapefruit, the researchers estimate.
(Source: Diabetes, 2011; doi: 10.2337/db10-0589).